Low-profile surface mount filter

ABSTRACT

Embodiments of the present invention provide low-profile surface mount filters. One embodiment of the present invention includes a filter housing adapted to mount on a substrate block having a plurality of flow paths and a filter cavity defined therein. The filter cavity is defined to extend in a generally horizontal direction when the low-profile filter is in use. A first flow passage is defined to connect an inlet of the filter housing to a first section of the filter cavity and a second flow passage is defined to connect a second section of the filter cavity to an outlet of the filter housing. A filter assembly is disposed in the filter cavity and sealed to the surface of the filter cavity separating the filter cavity into adjacent sections including the first section of the filter cavity and second section of the filter cavity.

RELATED APPLICATIONS

This application is a divisional of and claims priority under 35 U.S.C.§120 to U.S. patent application Ser. No. 12/509,970, entitled“Low-Profile Surface Mount Filter”, by DiPrizio et al., filed Jul. 27,2009, which is a divisional of U.S. patent application Ser. No.11/353,294, entitled “Low Profile Surface Mount Filter”, by DiPrizio etal., filed Feb. 10, 2006, which are hereby fully incorporated byreference herein.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to filters and more particularly tolow-profile surface mount filters.

BACKGROUND OF THE INVENTION

Many manufacturing processes require delivery of relatively high puritygases at regulated flow rates and pressures. In the manufacture ofsemiconductors, for example, the purity and flow rate of a gas must becarefully regulated to prevent defects on a wafer. The loss of a waferdue to a defect is both expensive and time consuming.

In semiconductor manufacturing, gas is provided to a process chamberthrough a “gas stick.” A gas stick can include a variety of componentssuch as filters, valves, mass flow controllers, pressure transducers orother components to purify the gas, regulate gas flow or monitorproperties of the gas or gas flow. Traditionally, components wereconnected in an “in-line” fashion with each component connected to thenext component by a VCR connector. More recently, the semiconductorindustry has moved to modular architectures. In a modular architecture,the gas components mount to modular substrate blocks. Flow passages inthe substrate blocks route flow between the substrate blocks and hencethe gas components. Modular architectures provide the advantage of areduced footprint and standardization of interfaces.

FIG. 1 illustrates one embodiment of a gas stick 100 using a modulararchitecture. In the example of FIG. 1, pressure transducer 102 ismounted on substrate block 104 and filter 106 is mounted on substrateblock 108. Gas stick 100 requires substrate 108 to accommodate thestandalone filter 106. The additional substrate 108 makes gas stick 100longer, heavier and more expensive.

Several attempts have been made to shorten the gas stick by using astackable filter. Prior filters have been made that have a purificationelement sandwiched between two sections of a block or purificationelements vertically aligned with the various flow passages to/from thesubstrate or components stacked on top of the filter. The first type offilter suffers the disadvantage of requiring multiple seals betweenvarious sections of the filter block. The additional mechanical sealscan interrupt the flow path, increase wetted surface area and increasedead space. Additionally, the seals may leak due to dimensional orsurface finish irregularities between the sealing surfaces of thesections of the filter block. The second type of filter (e.g., thefilter in which the purification element is aligned with a flowpassage), requires additional height to accommodate the purificationelement.

Consequently, there is a need for a low-profile filter that minimizesmechanical seals, gas stick length and height while fitting thefootprint of modular substrates.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide systems and methods forlow-profile filters that substantially eliminate or reduce thedisadvantages of previously developed filter systems and methods. Moreparticularly, embodiments of the present invention provide a low-profilefilter for use with modular gas panel designs. One embodiment of thepresent invention includes a filter housing adapted to mount on asubstrate block having a plurality of flow paths and a filter cavitydefined therein. The filter cavity is defined to extend in a generallyhorizontal direction when the low-profile filter is in use. A first flowpassage is defined to connect an inlet of the filter housing to a firstsection of the filter cavity and a second flow passage is defined toconnect a second section of the filter cavity to an outlet of the filterhousing. A filter assembly comprising a filter and adapter is disposedin the filter cavity and sealed to the surface of the filter cavityseparating the filter cavity into adjacent sections including the firstsection of the filter cavity and second section of the filter cavity.

The filter housing can be a unitary piece of material. The filters caninclude nickel, steel, ceramic TEFLON or other material disk or tubefilters. The flow passages, according to various embodiments of thepresent invention, can be arranged such that the gas is filtered beforethe gas is routed to a component mounted on top of the filter or afterthe gas returns from the component. According to other embodiments, thefilter can act as a standalone filter in which gas is received from thesubstrate block, filtered, and returned to the substrate block.

Another embodiment of the present invention can include a method forfiltering a gas using a low-profile filter comprising mounting a filterto a substrate block, directing the gas from an inlet in a filterhousing to a generally horizontal first filter cavity, flowing the gasinto a first filter assembly in a generally horizontal direction andthrough a first filter to filter the gas, and directing the gas from thefirst filter cavity to an outlet in the filter housing. Again, gas canbe filtered before or after the gas is routed to a component mounted onthe low-profile filter. According to other embodiments, the gas can bereceived from the substrate block, filtered and returned to thesubstrate block.

Yet another embodiment of the present invention includes a method ofmaking a low-profile filter comprising, forming a filter housing havinga top and bottom surface, machining a filter cavity into the filterhousing, wherein the filter cavity is oriented to be generallyhorizontal in use, machining a first flow passage into the filterhousing, wherein the first flow passage runs from an inlet in the filterhousing to the filter cavity and machining a second flow passage intothe filter housing wherein the second flow passage leads from the filtercavity to an outlet, forming a filter assembly and sealing the filterassembly to a surface of the filter cavity to separate the filter cavityinto adjacent sections, wherein the first flow passage enters the filtercavity in a first section and the second flow passage enters the filtercavity in a second section.

Embodiments of the present invention provide a technical advantage overpreviously developed filters by providing a low-profile surface-mountfilter that creates a sufficient pressure drop and has a sufficient logreduction value (“LRV”) for semiconductor manufacturing applications,while minimizing height.

Embodiments of the present invention provide another advantage byreducing the number of seals in a flow path, thereby reducing wettedsurface area and dead space internal to the filter. This can decreasethe time it takes to dry the filter (i.e., decrease dry down time) andminimize the potential of stray particles from becoming dislodged fromthe dead spaces and entering the gas stream.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and theadvantages thereof may be acquired by referring to the followingdescription, taken in conjunction with the accompanying drawings inwhich like reference numbers indicate like features and wherein:

FIG. 1 illustrates one embodiment of a gas stick using a modulararchitecture and a standalone filter with its required substrate;

FIG. 2 illustrates an embodiment of a shortened gas stick using alow-profile filter mounted between a substrate block and a component;

FIG. 3 illustrates an embodiment of a gas stick with a low-profilefilter acting as a standalone filter;

FIG. 4A and FIG. 4B are diagrammatic representations of a low-profilefilter;

FIG. 5 is a diagrammatic representation of a cutaway view of anembodiment of a low-profile filter according to FIG. 4A;

FIG. 6 is a diagrammatic representation of another cutaway view of anembodiment of a low-profile filter according to FIG. 4A;

FIG. 7 is a diagrammatic representation of another embodiment of alow-profile filter;

FIG. 8 is a diagrammatic representation of a cutaway view of thelow-profile filter of FIG. 7;

FIG. 9A and FIG. 9B are diagrammatic representations of anotherembodiment of a low-profile filter;

FIG. 10 is a diagrammatic representation of another embodiment of alow-profile filter;

FIG. 11 is a diagrammatic representation of an embodiment of making afilter assembly;

FIG. 12 is a cutaway view of another embodiment of a low-profile filter;

FIG. 13 is a cutaway view of another embodiment of a low-profile filter;and

FIG. 14 is a diagrammatic representation of a sealing mechanism for alow-profile filter.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention are illustrated in theFIGURES, like numerals being used to refer to like and correspondingparts of the various drawings.

Embodiments of the present invention provide a system and method for alow-profile filter. The low-profile filter includes, according to oneembodiment, a filter housing with ports on the top and bottom for gasingress/egress. The filter body defines a filter cavity runninggenerally horizontal through the filter body. A filter assembly dividesthe filter cavity into two horizontally adjacent sections. A first flowpassage leads from a port on the top or bottom of the filter body to thefirst section while a second flow passage leads from another port on thetop or bottom to the second section. Based on the configuration of theports and flow passages, the gas can be filtered before or after the gasflows to a component mounted on top of the low-profile filter.

The filter assembly, according to one embodiment, can include a tubefilter and an adapter. The adapter can be a ring or other shape that iscoupled to the tube filter and sealed to surface of the filter cavity.When seated in the filter cavity, the filter assembly segregates thefilter cavity into two horizontally adjacent sections with the tubefilter projecting into one of the sections. Gas enters the first sectionvia the first flow passage, flows through the center of the adapter andpermeates into the second section through the tube filter. The gas canthen flow out of the second section of the filter cavity via the secondflow passage.

According to another embodiment, the filter assembly can include one ormore vertical disk membranes sealed across the filter cavity (e.g.,generally in a plane normal to the primary horizontal axis of the filtercavity). In this example, gas enters into the first section via thefirst flow passage, flows through the disk membrane to the secondsection of the filter cavity and out of the filter cavity via the secondflow passage.

The flow passages can be configured and ports arranged such that the gasis filtered before flowing to a component stacked on top of thelow-profile filter or after flowing from the component stacked on top ofthe low-profile filter. Additionally, the flow passages and ports can beconfigured such that the low-profile filter acts as a standalone filter.

FIG. 2 illustrates an embodiment of a gas stick 200 with an example of alow-profile filter 210 according to embodiments of the presentinvention. In the example of FIG. 2, low-profile filter 210 is mountedbetween substrate block 212 and pressure transducer 214. In comparisonto FIG. 1, one substrate block is eliminated, thereby shortening the gasstick. Additionally, filter 210 is noticeably shorter than filter 106.Low-profile filter 210 can be configured to filter gas before the gasflows to pressure transducer 214, after gas leaves pressure transducer214 or both.

In operation, gas enters the bottom of low-profile filter 210 throughsubstrate block 212. The gas can either be filtered and passed topressure transducer 214 or passed pressure transducer 214 and filteredon the way back to substrate block 212. Low-profile filter 210 can beconfigured to fit a variety of substrate blocks and can be formed to becompatible with, K1S, K1, K1H, C-Seal, W-Seal, CS-Seal or other gaspanel substrate blocks known or developed in the art. Additionally,other components than pressure transducer 214 can be mounted tolow-profile filter 210 including, but not limited to, mass flowcontrollers, displays, moisture monitors, gauges, valves, diffusers,pressure regulators or other components known or developed in the art.

FIG. 3 illustrates another embodiment of a gas stick 300 utilizing anembodiment of a low-profile filter 310 mounted on substrate block 312.In the example of FIG. 3, low-profile filter 310 is a standalone filter.However, as in the example of FIG. 2, low-profile filter 310 isnoticeably shorter than filter 106. In this example, the gas enterslow-profile filter 310 from substrate block 312, passes through a filterand returns to substrate block 312.

FIGS. 4A and 4B are diagrammatic representations of one embodiment of alow-profile filter 210. Low-profile filter 210 includes a filter housing400 having a generally horizontal filter cavity 402 therein. Althoughonly shown as originating from surface 404, filter cavity 402 canoriginate from additional exterior surfaces of filter housing 400 tofacilitate insertion of filter assembly 430 (discussed below). One ormore ports (e.g., port 406, port 408, port 410, port 412) on the topsurface and bottom surface of filter housing 400 act as inlets oroutlets to low-profile filter 210. Flow passages defined in filterhousing 400 lead gas to/from filter cavity 402 and to/from theinlet/outlet ports. For example, flow passage 414 runs from bottom port406 to filter cavity 402 while flow passage 416 runs from filter cavity402 to top port 410. Flow passage 418 is a pass through passage runningbetween bottom port 408 and top port 412. Filter housing 400 can furtherinclude various connector holes (one of which is indicated at 420) toallow filter housing 400 to be connected to a substrate block.

Filter housing 400 is formed of a material suitable for directing gasflow such as stainless steel, though other materials can be used.Various characteristics of filter housing 400 can be configured to allowlow-profile filter 210 to be compatible with a variety of substrateblocks and components. By way of example, but not limitation,low-profile filter 210 can be compatible with a C-Seal architecture.Consequently, filter housing 400 can be 1.125 inches wide, 1.125 inchesdeep (i.e., can have approximately the same footprint as a C-Sealsubstrate block) and 0.375 inches high. In this example, port 406 willact as the inlet port to low-profile filter 210, port 410 will act asthe outlet port to provide gas to a component stacked on top oflow-profile filter 210 (i.e., according to the C-Seal architecture, thecenter port is the inlet port of a component), port 410 will providefiltered gas to the stacked component and port 408 will be the outletport to the substrate block. Thus, for the component stacked on top oflow-profile filter 210, filter housing 400 can provide the same portarrangement as a C-Seal substrate block.

Filter housing 400, according to one embodiment, is a unitary stainlesssteel block. Filter cavity 402, ports 406, 408, 410, and 412 aremachined into the stainless steel block using known machiningtechniques. Filter cavity 402, for example, can have a diameter of 0.276inches. The various flow passages and mounting holes can then bedrilled. It should be noted that some semiconductor manufacturersspecify that the hole in the center of a C-seal port leading to a flowpassage can have a major diameter of no larger than 0.180 inches. Theangle of the flow passage and diameter of flow passage can be chosensuch that the circle or ellipse (if drilled at an angle) at the entranceof the flow passage is no greater than a specified size (e.g., 0.180inches). Assuming flow passage 416 is drilled at an angle to the topsurface of housing 400 such that an elliptical inlet is formed, theangle and diameter of flow passage 416 running from filter cavity 402 toport 410 can be selected so that the major diameter of the inlet is nogreater than 0.180 inches or other specified size.

According to one embodiment, flow passage 414 from port 406 to filtercavity 402 is machined in two stages. The first portion is machined frominlet port 406 into filter housing 400. Again, the angle and radius offlow passage 416 can be selected such that the elliptical inlet to flowpassage 416 does not exceed specified dimensions. The second portion offlow passage 416 can be machined inward from the surface of filtercavity 402 at an angle to meet with the first section of flow passage414. The portion of flow channel 414 machined first will typically havea slightly larger diameter than the portion machined second, making iteasier to ensure that the second portion cleanly meets the first portionduring machining. For example, the first portion of flow passage 414 canhave a diameter of 0.125 inches while the diameter of the second portion(the smaller portion) can be 0.094 inches. Flow passage 416, accordingto one embodiment, can also have a diameter of approximately 0.125inches, while flow passage 420 can have a diameter up to 0.180 inches inthis example. It should be noted, however, any machining techniques canbe used to form filter housing 400.

A filter assembly 430 is disposed in filter cavity 402 and separatesfilter cavity 402 into two horizontally adjacent sections, showngenerally at 432 and 434 (see, FIG. 5). Flow passage 414 enters filtercavity 402 in section 432 and flow passage 416 enters filter cavity insection 434. Thus, the flow passage from the inlet port 406 to thefilter cavity 402 (i.e., flow passage 414) and the flow passage fromfilter cavity 402 to the outlet port 410 are segregated by filterassembly 430.

According to the embodiment of FIG. 4, filter assembly 430 includes tubefilter 438 coupled to adapter 440. However, filter assembly 430 caninclude any filter mechanism for segregating filter cavity 402 such thatgas is filtered between the sections. Tube filter 438 can include anytube filter suitable for a set of process requirements. By way ofexample, but not limitation, tube filter 438 can be a 0.003 micronstainless steel or nickel filter. Examples of steel and nickel tubefilters include Mykrolis Corp. Wafergard SL Gas Filters WGSLSFC1M andWGSLNFC1M respectively in these examples the wall thickness is about0.020-0.065 inches with a pore size of 5-10 microns. (Mykrolis Corp. isbased in Billerica, Mass. and has merged with Entegris Corp. of Chaska,Minn.) Other examples of filter materials include ceramic, TEFLON andother filter materials (TEFLON is a registered trademark of E.I. du Pontde Nemours and Company of Wilmington, Del.). Adapter 440 can bestainless steel or other material.

Tube filter 438 is welded or otherwise coupled to adapter 440 to formfilter assembly 430. The filter assembly is inserted into filter cavity402 and a seal formed between filter assembly 430 and the walls offilter cavity 402. According to one embodiment, the seal is formedthrough an interference fit between adapter 440 and the wall of filtercavity 402. According to this embodiment, the radius or outer dimensionof adapter 440 is slightly larger than the radius or outer dimension offilter cavity 402 at the area where adapter 440 will seal with the wallof filter cavity 402. For example, at ambient temperature adapter 440can have a radius of be 0.0005-0.0015 inches greater than the radius offilter cavity 402 in the area that the seal is to be formed. Filterassembly 430 can be forced into filter cavity 402 using a press to formthe interference seal between adapter 440 and filter cavity 402.According to another embodiment, filter assembly 430 can be chilled(e.g., with liquid Nitrogen or other chilling method) and filter housing400 heated. While filter assembly 430 is contracted due to cooling andfilter cavity 402 dilated due to heating, filter assembly 430 is placedin filter cavity 402. As filter assembly 430 and filter housing 400reach ambient temperature, an interference seal will form between filteradapter 440 and the walls of filter cavity 402. In another embodimentthe filter assembly 430 can be welded to the filter cavity 402 usinge-beam, laser, tag or plasma.

Filter cavity 402 can be sealed at surface 404 using a sealing button,plug or other piece of material 424 (shown in FIG. 4B and FIG. 5). Thesealing button can be formed of stainless steel or other material thatis preferably non-reactive or minimally reactive with the intendedprocess gas. According to one embodiment, sealing button is sealed tofilter housing 400 using a fusion weld.

In operation, low-profile filter 210 is mounted to a substrate, as shownin FIG. 2. Gas enters flow passage 414 through port 406 and flows tosection 432 of filter cavity 402. The gas then flows through the centerof adapter 440 into tube filter 438 and permeates through the wall oftube filter 438 into section 434 of filter cavity 402. The filtered gasflows from filter cavity 402 to port 410 via flow passage 416 to acomponent mounted on low-profile filter 210.

According to other embodiments, flow passage 414 can enter filter cavity402 in section 434 and flow passage 416 can enter filter cavity 402 insection 432. Consequently, gas will be filtered by passing from theoutside of tube filter 438 to the inside of tube filter 438.

FIG. 5 is a diagrammatic representation of a cutaway view of low-profilefilter 210 showing filter cavity 402 from the side. Shown in FIG. 5 isfilter housing 400 including bottom port 406, top ports 410 and 412 andfilter cavity 402. FIG. 5 also illustrates filter assembly 430 includingtube filter 438 and adapter 440. Sealing button 424 is also shown. Ascan be seen in FIG. 5, filter assembly 430 separates filter cavity 402into horizontally adjacent section 432 and section 434. Flow passage 414runs from bottom port 406 to filter cavity 402 while flow passage 416runs from port 410 to filter cavity 402. In this example, gas flows froma substrate block into port 406 and enters filter cavity 402 via flowpassage 414 in section 432. The gas flows through the center of adapter440 into the center of tube filter 438 and permeates out of tube filter438 into section 434. The gas then flows out of filter cavity 402through flow passage 416 and through port 410 to a component mounted onlow-profile filter 210. The gas returns from the component through port412 and is lead back to the substrate block. In this example, the gas isfiltered prior to entering the component.

FIG. 6 is a diagrammatic representation of a cutaway view of low-profilefilter 210 of FIG. 4A. FIG. 6 illustrates filter housing 400, port 406,port 408, port 410, port 412, flow passage 416, flow passage 418 andtube filter 438. According to one embodiment, flow passage 416 directsgas filtered by tube filter 438 to a component mounted on low-profilefilter 210. Gas returning from the component enters filter housing 400at port 412. Flow passage 418 is a pass-through flow passage that leadsthe gas from port 412 to port 408 and the underlying substrate block.

In the previous embodiments, low-profile filter 210 filters gas prior toproviding the gas to the component mounted on low-profile filter 210. Inother embodiments, however, low-profile filter 210 can filter the gasafter has been output by the component back to low-profile filter 210.FIG. 7 is a diagrammatic representation of a low-profile filter 210 forfiltering gas on the outlet side of the component. According to theembodiment of FIG. 7, low-profile filter 210 includes a filter housing700 having a generally horizontal filter cavity 702 therein. Althoughonly shown as originating from surface 704, filter cavity 702 canoriginate from additional exterior surfaces of filter housing 700 tofacilitate insertion of filter assembly 730 (discussed below). One ormore ports (e.g., port 706, port 708, port 710, port 712 (ports 706 and708 are better viewed in FIG. 8)) on the top surface and bottom surfaceof filter housing 700 act as inlets or outlets to low-profile filter210. Flow passages defined in filter housing 700 lead gas to/from filtercavity 702 and to/from the inlet/outlet ports. For example, flow passage714 runs from bottom port 706 to top port 710. Flow passage 716 runsfrom top port 712 to filter cavity 702 while flow passage 718 (shown inFIG. 8) runs from filter cavity 702 to bottom port 708. Filter housing700 can further include various connector holes (indicated at 720) toallow filter housing 700 to be connected to a substrate block. Filterhousing 700 can be formed of a unitary block of material and can bedimensioned and machined in a manner similar to that described inconjunction with filter housing 400 of FIGS. 4A and 4B but with the flowpassages arranged to provide outlet side filtering.

A filter assembly 730 is disposed in filter cavity 702 and separatesfilter cavity 702 into two horizontally adjacent sections, showngenerally at 732 and 734 (shown in FIG. 8). Flow passage 716 entersfilter cavity 702 in section 732 and flow passage 718 enters filtercavity in section 734. Thus, the flow passage from the top inlet port712 to the filter cavity 702 (i.e., flow passage 716) and the flowpassage from filter cavity 702 to the bottom outlet port 708 (i.e., flowpassage 718) are segregated by filter assembly 730.

According to the embodiment of FIG. 7, filter assembly 730 includes tubefilter 738 coupled to adapter 740 (better seen in FIG. 8). However,filter assembly 730 can include any filter mechanism for segregatingfilter cavity 702 such that gas is filtered between the sections. Tubefilter 738 can include any tube filter suitable for a set of processrequirements. By way of example, but not limitation, tube filter 738 canbe a 0.003 micron stainless steel or nickel filter. Adapter 740 can bestainless steel or other material.

Filter assembly 730 can be formed in a similar manner as filter assembly430 of FIG. 4A and can be coupled to filter housing 700 to form aninterference seal or other seal. Filter cavity 702 can be sealed atsurface 704 using a sealing button 724 (shown in FIG. 8) or other pieceof material. Button 724 can be formed of stainless steel or othermaterial that is preferably non-reactive or minimally reactive with theintended process gas. According to one embodiment, button 724 is sealedto filter housing 700 using a fusion weld.

In operation, low-profile filter 210 is mounted to a substrate, as shownin FIG. 2. Gas enters flow passage 714 through port 706 and flows to thecomponent mounted on top of low-profile filter 210 via port 710. Thecomponent returns the gas to low-profile filter 210 via port 712. Thegas flows through flow passage 716 to filter cavity 702. The gas thenflows through the center of adapter 740 into tube filter 738 andpermeates through the wall of tube filter 738 into section 734 of filtercavity 702. The filtered gas flows from filter cavity 702 to port 708via flow passage 718 back to the substrate upon which low-profile filter210 is mounted.

According to other embodiments, flow passage 716 can enter filter cavity702 in section 734 and flow passage 718 can enter filter cavity 702 insection 732. Consequently, gas will be filtered by passing from theoutside of tube filter 738 to the inside of tube filter 738. Regardless,filtering gas on the outlet side of the mounted component provides theadvantage that any contaminants introduced by the component are filteredbefore the gas is routed to other components.

FIG. 8 is a diagrammatic representation of a cutaway view of low-profilefilter 210 of FIG. 7. Shown in FIG. 8 is filter housing 700 includingbottom ports 706 and 708, top ports 710 and 712 and filter cavity 702.Also shown is filter assembly 730 including tube filter 738 and adapter740. FIG. 8 further illustrates sealing button 724. As can be seen inFIG. 8, filter assembly 730 separates filter cavity 702 intohorizontally adjacent section 732 and section 724. Flow passage 716 runsfrom top port 712 to filter cavity 702 while flow passage 718 runs fromfilter cavity 702 to bottom port 708. In this example, gas flows from asubstrate block into port 706 and through to port 710. On the returnpath from the component mounted to low-profile filter 210, the gas flowsfrom port 712 to filter cavity 702, through the center of adapter 740into the center of tube filter 738 and permeates out of tube filter 738into section 734. The gas then flows out of low-profile filter 210through port 708 to the substrate block. Again, however, the orientationof flow passages can be reversed such that gas is filtered by passinggas from the outside of tube filter 738 to the center of tube filter738.

Previously described embodiments of the present invention utilize asingle filter. According to another embodiment of the present invention,multiple filters can be used. FIGS. 9A and 9B are diagrammaticrepresentations of one embodiment of a dual filter configurationlow-profile filter 210. According to the embodiment of FIGS. 9A and 9B,low-profile filter 210 includes a filter housing 900 having a pair ofgenerally horizontal filter cavities 902 and 903 therein. Although onlyshown as originating from surface 904, filter cavities 902 and 904 canoriginate from additional exterior surfaces of filter housing 900 tofacilitate insertion of filter assemblies 930 and 931. One or more portson the top surface and bottom surface of filter housing 900 act asinlets or outlets to low-profile filter 210. From the perspective ofFIGS. 9A and 9B only top ports 910 and 912 are indicated. Flow passagesdefined in filter housing 900 lead gas to/from the filter cavities 902and 903 and to/from the inlet/outlet ports. For example, flow passage914 runs from a bottom port to filter cavity 902 and filter cavity 903.Furthermore, a flow passage leads from filter cavity 902 to port 910while another flow passage runs from filter cavity 903 to port 910. Theflow passage from port 912 to the bottom outlet port acts as a passthrough passage.

A filter assembly 930 is disposed in filter cavity 902 and a secondfilter assembly 931 is disposed in filter cavity 903. Filter assembly930 separates filter cavity 902 into two horizontally adjacent sections,while filter assembly 931 separates filter cavity 903 into twohorizontally sections. Flow passage 914 enters filter cavity 902 in thefirst section of filter cavity 902 and filter cavity 903 in the firstsection of filter cavity 903. The outlet flow passage (e.g., runningfrom filter cavity 902 to port 910) enters filter cavity 902 in thesecond section of filter cavity 902 while the outlet flow passage offilter cavity 903 (e.g., running from filter cavity 903 to port 910)enters filter cavity 903 in the second section of filter cavity 903.Thus, flow passage 914 is separated from the outlet of filter cavity 902by filter assembly 930 and the outlet of filter cavity 903 by filterassembly 931.

According to the embodiment of FIGS. 9A and 9B, filter assembly 930 andfilter assembly 931 can be similar to the previously described filterassemblies and can include an adapter and tube filter. However, eitherfilter assembly can include any filter mechanism for segregating therespective filter cavity into sections such that gas is filtered betweenthe sections. By way of example, but not limitation, the tube filterscan be a 0.003 micron stainless steel or nickel filter while theadapters can be stainless steel or other material.

Filter assemblies 930 and 931 can be formed in a similar manner asfilter assembly 430 of FIG. 4A and FIG. 4B and can be coupled to filterhousing 900 to form an interference seal or other seal. Filter cavity902 and filter cavity 903 can be sealed at surface 904 using a sealingbutton or plug formed of stainless steel or other material that ispreferably non-reactive or minimally reactive with the intended processgas. The plugs or sealing buttons can be sealed to filter housing 900using a fusion weld.

In operation, low-profile filter 210 is mounted to a substrate, as shownin FIG. 2. Gas enters flow passage 914 through a bottom port and flowsto filter cavity 902 and 903. The gas flows through the center of filterassemblies 930 and 931 and permeates into the other sections of filtercavity 902 and 903, respectively. Again, however, this flow can bereversed such that the gas is filtered by flowing into, rather than outof, the tube filters. Flow passages direct gas to port 910 from filtercavity 902 and filter cavity 903. Gas returns from component throughport 912, through a pass through flow passage and out an outlet port onthe bottom of filter housing 900. Thus, the flow path is similar to thatdescribed in conjunction with FIGS. 4A, 4B and 5 except that the gas isdirected to two filter cavities in parallel to filter the gas before thegas is directed to the component stacked on top of low-profile filter210.

In the example of FIG. 9A-9B, low-profile filter 210 acts as an inletfilter. However, low-profile filter 210 can be configured as a dualfilter for the outlet side of a component. According to anotherembodiment, one filter can act on the inlet side of the component whilethe other filter can act on the outlet side of the component. Accordingto other embodiments, both filter can be in the same filter cavity(e.g., inserted from each end) and the gas recirculated through thefilter cavity.

The use of dual filters provides an advantage over a single filterbecause the dual filters can provide for greater surface area using asmall diameter. This can allow for a greater or similar pressure drop toa single filter, while allowing the height of filter housing 900 to bereduced. Additionally, multiple smaller diameter filters can be used forfilter housings in which the port placement does not allow a largerfilter to fit.

FIG. 10 is a diagrammatic representation of yet another embodiment oflow-profile filter 210. Low-profile filter 210 includes a filter housing1000 having a generally horizontal filter cavity 1002 therein. Althoughonly shown as originating from one surface, filter cavity 1002 canoriginate from additional exterior surfaces of filter housing 1000 tofacilitate insertion of filter assembly 1030. One or more ports (e.g.,port 1006, port 1008, port 1010, port 1012) on the top surface andbottom surface of filter housing 1000 act as inlets or outlets tolow-profile filter 210. Flow passages defined in filter housing 1000lead gas to/from filter cavity 1002 and to/from the inlet/outlet ports.For example, flow passage 1014 runs from bottom port 1006 to filtercavity 1002 while flow passage 1016 runs from filter cavity 1002 to topport 1010. Flow passage 1018 is a pass through passage running betweenbottom port 1008 and top port 1012. Filter housing 1000 can furtherinclude various connector holes to allow filter housing 1000 to beconnected to a substrate block.

A filter assembly 1030 is disposed in filter cavity 1002 and separatesfilter cavity 1002 into two horizontally adjacent sections. Flow passage1014 enters filter cavity 1002 in the first section and flow passage1016 enters filter cavity in the second section. Thus, the flow passagefrom the inlet port 1006 to the filter cavity 1002 (i.e., flow passage1014) and the flow passage from filter cavity 1002 to the outlet port1010 are segregated by filter assembly 1030.

According to the embodiment of FIG. 10, filter assembly 1030 includestube filter 1038 coupled to adapter 1040. However, filter assembly 1030can include any filter mechanism for segregating filter cavity 1002 suchthat gas is filtered between the sections. Tube filter 1038 can includeany tube filter suitable for a set of process requirements. Tube filter1038, according to one embodiment of the present invention, is a TEFLONfilter comprising multiple TEFLON tubes (e.g., hollow fibers) that areopen to the first section. The tubes can optionally be straight tubesor, for example, “U” shaped tubes. Adapter 1040 can be a stainless steelring. Examples of similar TEFLON tubes can be found in Mykrolis Corp.pHasor Membrane Contactor PH2005F0F. According to one embodiment, theTEFLON tubes have a pore size of approximately 5 microns and a wallthickness of 0.006-0.012 inches, though the pore size, tube length andwall thickness can be controlled during the process of making the tubes.A layer of TEFLON seals the gaps between the TEFLON tubes and betweenthe TEFLON tubes and adapter 1040. One embodiment for forming filterassembly 1030 is described in greater detail in conjunction with FIG.11.

Filter assembly 1030 is inserted into filter cavity 1002 and a sealformed between filter assembly 1030 and the walls of filter cavity 1002.According to one embodiment, the seal is formed through an interferencefit between adapter 1040 and the wall of filter cavity 1002. Accordingto this embodiment, the radius or outer dimension of adapter 1040 isslightly larger than the radius or outer dimension of filter cavity 1002at the area where adapter 1040 will seal with the wall of filter cavity1002. For example, at ambient temperature adapter 1040 can have adiameter of be 0.001 to 0.002 inches greater than the diameter of filtercavity 1002 in the area that the seal is to be formed. Filter assembly1030 can be forced into filter cavity 1002 using a press to form theinterference seal between adapter 1040 and filter cavity 1002. Accordingto another embodiment, filter assembly 1030 can be chilled (e.g., withliquid Nitrogen or other chilling method) and filter housing 1000heated. While filter assembly 1030 is contracted due to cooling andfilter cavity 1002 dilated due to heating, filter assembly 1030 isplaced in filter cavity 1002. As filter assembly 1030 and filter housing1000 reach ambient temperature, an interference seal will form betweenfilter adapter 1040 and the walls of filter cavity 1002.

Filter cavity 1002 can be sealed at the surface of housing 1000 using asealing button 1024 or other piece of material. Button 1024 can beformed of stainless steel or other material that is preferablynon-reactive or minimally reactive with the intended process gas.According to one embodiment, button 1024 is sealed to filter housing1000 using a fusion weld.

In operation, low-profile filter 210 is mounted to a substrate, as shownin FIG. 2. Gas enters flow passage 1014 through port 1006 and flows intothe first section of filter cavity 1002. The gas then flows through theopen ends of the TEFLON tubes exposed to the first section of filtercavity 1002 and permeates through the walls of the tubes into the othersection of filter cavity 1002. The filtered gas flows from filter cavity1002 to port 1010 via flow passage 1016 to a component mounted onlow-profile filter 210. According to other embodiments, the flowpassages can be arranged such that gas will be filtered by passing fromthe outside of tube filter 1038 to the inside of the TEFLON tubes.

In the example of FIG. 10, gas is filtered on the inlet side ofcomponent mounted to low-profile filter 210. According to otherembodiments, gas can be filtered on the outlet side of the component orboth the inlet and outlet side. Additionally, multiple TEFLON (or othermaterial) filters can be used to filter can on the inlet side, outletside or both.

FIG. 11 illustrates one embodiment of forming filter assembly 1030.Adapter 1040 and multiple TEFLON tubes (e.g., such as tube 1102) areplaced in a crucible 1103. Small TEFLON beads are interspersed betweenthe tubes (e.g., beads 1104) to act as a potting material. Preferably,beads 1104 have a lower melting temperature than the TEFLON tubes andadapter 1040. For example, TEFLON tubes can be PFA TEFLON while theTEFLON beads can be MFA TEFLON. The crucible is heated to a temperaturethat melts beads 1104, but not the TEFLON tubes or adapter 1040. Whenthe beads have melted to fill in the gaps between the tubes and the gapsbetween the tubes and adapter 1040, the crucible can be cooled toambient temperature to allow the melted TEFLON to cool into TEFLON seal1106. The end of the TEFLON tubes can then be cut off to ensure that thetubes are not plugged by the TEFLON seal 1106. For example, the tubescan be made flush with adapter 1040. While TEFLON seal 1106 may not bondcompletely with adapter 1040 (e.g., due to the respective materialproperties of the TEFLON and adapter), a mechanical seal between theTEFLON seal 1106 and adapter 1040 can be completed when adapter 1040 isdeformed through establishing the interference fit with filter housing1000 (i.e., when the adapter is “squeezed” by the filter cavity walls toform an interference fit).

Thus far, the low-profile filter has been described in the context of afilter that is located between a substrate block and a component.According to other embodiments of the present invention, however,low-profile filter can be a standalone filter (e.g., low-profile filter310 of FIG. 3). FIG. 12 is a diagrammatic representation of oneembodiment of a cutaway view of low-profile filter 310. Low-profilefilter 310 includes a filter housing 1200 having a generally horizontalfilter cavity 1202 therein. Although only shown as originating from onesurface, filter cavity 1202 can originate from additional exteriorsurfaces of filter housing 1200 to facilitate insertion of filterassembly 1230. One or more ports (e.g., port 1206, and port 1208) on thebottom surface of filter housing 1200 act as inlets or outlets tolow-profile filter 310. Flow passages defined in filter housing 1200lead gas to/from filter cavity 1202 and to/from the inlet/outlet ports.For example, flow passage 1214 runs from bottom port 1206 to filtercavity 1202 while flow passage 1216 runs from filter cavity 1202 tobottom port 1208. Filter housing 1200 can further include variousconnector holes (indicated at 1220) to allow filter housing 1200 to beconnected to a substrate block.

Filter housing 1200 is formed of a material suitable for directing gasflow such as stainless steel, though other materials can be used.Various characteristics of filter housing 1200 can be configured toallow low-profile filter 310 to be compatible with a variety ofsubstrate blocks and components. By way of example, but not limitation,low-profile filter 310 can be compatible with a C-Seal architecture.

A filter assembly 1230 is disposed in filter cavity 1202 and separatesfilter cavity 1202 into two horizontally adjacent sections, showngenerally at 1232 and 1234. Flow passage 1214 enters filter cavity 1202in section 1232 and flow passage 1216 enters filter cavity in section1234. Thus, the flow passage from the inlet port 1206 to the filtercavity 1202 (i.e., flow passage 1214) and the flow passage from filtercavity 1202 to the outlet port 1208 are segregated by filter assembly1230. Filter assembly 1230 can include a filter assembly similar tofilter assemblies 430, 730, 930, 931, 1030 or other filter assemblies.

In operation, low-profile filter 310 is mounted to a substrate, as shownin FIG. 3. Gas enters flow passage 1214 through port 1206 and flows tosection 1232 of filter cavity 1202. The gas then flows through thecenter of adapter 1240 into tube filter 1238 and permeates through thewall of tube filter 1238 into section 1234 of filter cavity 1202. Thefiltered gas flows from filter cavity 1202 to port 1208 via flow passage1216 back to the substrate block.

According to other embodiments, flow passage 1214 can enter filtercavity 1202 in section 1234 and flow passage 1216 can enter filtercavity 1202 in section 1232. Consequently, gas will be filtered bypassing from the outside of tube filter 1238 to the inside of tubefilter 1238. Additionally, it should be understood that filter 310 caninclude multiple filter cavities for filtering the gas in parallel orseries.

FIG. 13 is a diagrammatic representation of another embodiment of thepresent invention. According to the embodiment FIG. 13 low-profilefilter 210 includes a filter housing 1300 having a generally horizontalfilter cavity 1302 therein. Although only shown as being open to onesurface, filter cavity 1302 can be open to additional exterior surfacesof filter housing 1300. Various ports and flow passages (not shown) canbe arranged in a manner similar to those previously described or inother suitable arrangements.

A filter assembly 1330 is disposed in filter cavity 1302 and separatesfilter cavity 1302 into three horizontally spaced sections, showngenerally at 1332, 1334 and 1335. The inlet to filter cavity 1302 entersin section 1332 and the outlet exits at section 1335. Gas enters filtercavity 1302, flows through filter assembly 1330 and exits filter cavity1302.

According to the embodiment of FIG. 13, filter assembly 1330 includesone or more disk filters (e.g., disk filters 1342, 1344) across filtercavity 1302 such that gas flows through the disk filters in a primarilyhorizontal direction. Each disk filter can include any filter suitablefor a set of process requirements, including by way of example but notlimitation, steel, ceramic, nickel or other disk filters. Adapter 1340is welded or otherwise coupled to the disk filters to form a seal. Asdescribed above, adapter 1340 can be sealed to housing 1300 using aninterference fit or other seal. While, in the example above, a singleadapter seats multiple disks, in other embodiments, multiple adapterscan be used.

Filter cavity 1302 can be sealed using a sealing button 1324 or otherpiece of material. Button 1324 can be formed of stainless steel or othermaterial that is preferably non-reactive or minimally reactive with theintended process gas. According to one embodiment, button 1324 is sealedto filter housing 1300 using a fusion weld. Thus, embodiments of thepresent invention can provide low-profile filters that uses one or moredisk filters to filter a gas.

In the previous embodiments, the seal between an adapter and filterhousing is primarily described as an interference seal caused by thedifference in size of the adapter and filter cavity, though other sealscan be used. FIG. 14 is a diagrammatic representation of an otherexample of a mechanical seal that can be used. In the embodiment of FIG.14, a metal or other material gasket 1402 (e.g., a steel ring or othergasket) is placed between filter housing 1406 and adapter 1404. Each offilter housing 1406 and adapter 1404 can include a thin protruding edge(e.g., edge 1408 and edge 1410). When adapter 1404 is pressed into thefilter cavity, the respective edges dig into gasket 1402, creating amechanical seal.

Embodiments of the present invention thus provide low-profile filtersthat can fit between components of a gas stick or act as a standalonefilter with minimal impact on overall gas stick height. The low-profilefilters can filter on the inlet side, outlet side or both sides of acomponent mounted thereon. While specific examples of dimensions andfilters have been used, these examples are for the purposes ofillustration. Other suitable dimensions and materials can be used.Moreover, any suitable filter, such as a pleated filter can be used.

Various embodiments of the present invention provide advantages overprior art filters by reducing the number of components required andreducing the number of seals per filter required. This reduces thenumber of seals that potentially interrupt the gas flow path, minimalinternal wetted surface are, minimal internal dead space, reducedlikelihood of leakage and reduced filter height.

Although the present invention has been described in detail herein withreference to the illustrative embodiments, it should be understood thatthe description is by way of example only and is not to be construed ina limiting sense. It is to be further understood, therefore, thatnumerous changes in the details of the embodiments of this invention andadditional embodiments of this invention will be apparent to, and may bemade by, persons of ordinary skill in the art having reference to thisdescription. It is contemplated that all such changes and additionalembodiments are within the scope of this invention as claimed below.

1. A method of making a low-profile filter comprising: forming a filterhousing having a top and bottom surface; machining a filter cavity intothe filter housing, wherein the filter cavity is oriented to begenerally horizontal in use; machining a first flow passage into thefilter housing, wherein the first flow passage runs from an inlet in thefilter housing to the filter cavity and machining a second flow passageinto the filter housing wherein the second flow passage leads from thefilter cavity to an outlet; forming a filter assembly; sealing thefilter assembly to a surface of the filter cavity to separate the filtercavity into adjacent sections, wherein the first flow passage enters thefilter cavity in a first section and the second flow passage enters thefilter cavity in a second section.
 2. The method of claim 1, whereinforming the filter assembly, further comprises coupling a filter to anadapter.
 3. The method of claim 2, wherein the filter is a disk filter.4. The method of claim 2, wherein the filter is a tube filter.
 5. Themethod of claim 4, wherein the filter is a metal tube filter and theadapter is a stainless steel adapter and wherein coupling the filter tothe adapter further comprises welding the filter to the adapter.
 6. Themethod of claim 1, further comprising creating an interference sealbetween the filter assembly and the surface of the filter cavity.
 7. Themethod of claim 6, further comprising creating the interference seal bypressing the filter assembly into the filter cavity with sufficientforce to create the interference seal.
 8. The method of claim 6, furthercomprising creating the interference seal by: heating the filter housingto dilate the filter cavity; cooling the filter assembly; inserting thefilter assembly into the filter cavity; and allowing the filter housingand filter assembly to reach ambient temperature.
 9. The method of claim1, further comprising sealing the end of the filter cavity.
 10. Themethod of claim 1, wherein the inlet to the filter housing is on thebottom surface of the filter housing and the outlet from the filterhousing is on the top surface of the filter housing.
 11. The method ofclaim 1, wherein the inlet to the filter housing and the outlet from thefilter housing are on the bottom surface of the filter housing.
 12. Themethod of claim 1, wherein the inlet to the filter housing is on the topsurface of the filter housing and the outlet is on the bottom surface ofthe filter cavity.
 13. The method of claim 1, wherein the filter housingis a unitary block of material.